Academic literature on the topic 'In vitro swallowing'

Abstract Drinks and foods may be thickened to improve swallowing safety for dysphagia patients, but the resultant consistencies are not always palatable. Characterising alternative appetising foods is an important task. The study aims to characterise the in vitro swallowing behaviour of specifically formulated thickened dysphagia fluids containing xanthan gum and/or starch with standard jellies and yoghurt using a validated mechanical model, the “Cambridge Throat”. Observing from the side, the model throat can follow an experimental oral transit time (in vitro-OTT) and a bolus length (BL) at the juncture of the pharynx and larynx, to assess the velocity and cohesion of bolus flow. Our results showed that higher thickener concentration produced longer in vitro-OTT and shorter BL. At high concentration (spoon-thick), fluids thickened with starch-based thickener showed significantly longer in vitro-OTT than when xanthan gum-based thickener was used (84.5 s ± 34.5 s and 5.5 s ± 1.6 s, respectively, p < 0.05). In contrast, at low concentration (nectar-like), fluids containing xanthan gum-based thickener demonstrated shorter BL than those of starch-based thickener (6.4 mm ± 0.5 mm and 8.2 mm ± 0.8 mm, respectively, p < 0.05). The jellies and yoghurt had comparable in vitro-OTT and BL to thickeners at high concentrations (honey-like and spoon-thick), indicating similar swallowing characteristics. The in vitro results showed correlation with published in vivo data though the limitations of applying the in vitro swallowing test for dysphagia studies were noted. These findings contribute useful information for designing new thickening agents and selecting alternative and palatable safe-to-swallow foods.

The purpose of the present investigation was to examine the influence of a nitric oxide scavenger, hemoglobin (Hb), on esophageal function. Intraluminal pressures of anesthetized opossums were recorded from lower esophageal sphincter (LES) and 1, 5, and 9 cm above the LES. The influence of a representative Hb-based oxygen carrier was examined on swallowing-induced esophageal peristalsis and LES relaxation. In in vitro studies, LES relaxation and esophageal peristaltic contractions were induced by the activation of nonadrenergic noncholinergic (NANC) neurons by electrical field stimulation (EFS). Hb caused significant impairment in swallowing- and EFS-induced LES relaxation and a significant increase in the speed of esophageal peristalsis. In some experiments, swallowing caused simultaneous contractions in the esophagus following Hb administration. Although Hb completely blocked LES relaxation by NO and significantly attenuated that by NANC nerve stimulation, it had no significant effect on isoproterenol-induced LES relaxations. The data support the role of NO in LES relaxation and esophageal peristalsis. This esophageal model may be important in understanding the influence of NO inhibitors and scavengers in gastrointestinal motility.

Swallowing oral solid dosage forms is challenging for those who have medication swallowing difficulties, including patients with dysphagia. One option is to mix the drug (whole or crushed) with a thick vehicle (medication lubricant). Previous in vitro studies consistently suggest that thick vehicles could impact the dissolution of solid dosage forms, potentially influencing their therapeutic effectiveness, but do not account for changes that happen during oral processing and swallowing. This study aims to investigate the potential impact of medication lubricants on drug release and examine the effect of oral processing. In vitro dissolution of whole and crushed paracetamol tablets mixed with five commercially available medication lubricants (two IDDSI level 2, two IDDSI level 3, and one IDDSI level 4) were tested with and without oral processing; a medication lubricant with/without paracetamol was placed in the mouth (five healthy volunteers), prepared for swallowing, but then expectorated and assessed for physical characteristics and drug release. Medication lubricants, both alone and mixed with crushed paracetamol tablets, showed a significant decrease in viscosity after oral processing. Without oral processing, IDDSI level 3 and 4 lubricants significantly delayed the dissolution of paracetamol tablets. After oral processing, particularly with crushed tablets, there was a substantial increase in the dissolution rate. These findings suggest that dissolution testing overestimates the impact of medication lubricants on drug dissolution. Therefore, using in vitro dissolution tests to predict the dissolution rate of medications mixed with thick vehicles is discouraged. It is essential to consider ways to incorporate the effects of the oral environment and oral processing on thick vehicles used for oral medication administration.

In vitro swallowing experiments suggest that thin, viscoelastic liquids with strong apparent extensional viscosity lead to fast transit, lower oral residues and a compact bolus leaving the oral cavity.

Orally disintegrating tablets (ODTs) are the preferred and accepted solid dosage forms by patients. These tablets disintegrate in the oral cavity within a short period, providing an advantage for individuals who have difficulty swallowing. Quality control of ODTs can be achieved through measures such as friability, porosity, hardness, wetting time, water absorption capacity, in vitro disintegration test, and dissolution test. This article summarizes the advantages and in vitro quality control tests of orally disintegrating tablets.

Introduction Orally disintegrating tablet (ODT) is a dosage form that overcomes the problem of swallowing which is prevalent in about 35% of the general population. Co-trimoxazole (CTX) is given for patients with HIV for the prophylaxis of opportunistic infection (OI), commonly for pneumocystis carinii pneumonia. It was reported that CTX was associated with a 25–46% reduction in mortality among individuals infected with HIV in sub-Saharan Africa. Esophageal candidiasis which usually comes along with HIV/AIDS is one of AIDS defining illness affecting up to 1 in 5 of people with AIDS. This opportunistic illness is manifested by painful or difficulty of swallowing. In this respect, CTX ODT offer the advantages of both liquid dosage forms in terms of easy swallowing thereby improve patient compliance and solid dosage forms in terms of dose uniformity, stability, lower production, and transportation costs. The objective of this study was to formulate, characterize and optimize CTX ODT which could overcome swallowing problem and improve patient compliance. Co-trimoxazole ODTs were prepared by direct compression technique using a semi synthetic super disintegrant (crospovidone) along with other excipients. Two taste masking techniques were employed, addition of sweetening agent, and solid dispersion by using a pH sensitive polymer, Eudragit E-100 at different ratios (1:1, 1:2 and 1:3). Taste masking was determined by comparing taste threshold value and in vitro drug release. Preliminary study was used to investigate the effect of crospovidone, compression force (CF) and Hydroxypropyl cellulose (HPC) on disintegration time, friability and wetting time (WT). Factorial design was used as it enables simultaneous evaluation of formulation variables and their interaction effect. From the preliminary study, the factors that were found significant were further optimized using central composite design. Design-Expert 8.0.7.1 software was employed to carry out the experimental design. The bitterness threshold concentration of Trimethoprim was found to be 150 μg/ml and the in vitro drug release of the three batches of drug to polymer ratio (F1:1, 1:2 and 1:3) was 2.80±0.05, 2.77±0.00 and 2.63±0.00 respectively. From the optimization study, the optimal concentration for the superdisintegrant was 8.60% w/w and a CF of 11.25 KN which gave a rapid disintegration and WT of 13.79 and 23.19 seconds respectively and a friability of 0.666%. Conclusion In this study, co-trimoxazole ODT was formulated successfully. Central composite design was effectively used to model and optimize friability, DT and WT. The method was found effective for estimating the effect of independent variables on the dependent variables by using polynomial equation and surface plots. Optimization of the response variables was possible by using both numerical and graphical optimization and the predicted optimal conditions were confirmed experimentally and were found to be in good agreement within 5% of the predicted responses. The results of the study showed that CTX ODT had significantly rapid disintegration, less than 1% friability and enhanced dissolution profiles. The successful formulation of CTX ODT can solve difficulty of swallowing of conventional tablets for some group of patients which are unable to swallow solid oral dosage form.

Swallowing disorders, or dysphagia, can lead to bolus aspiration in the airway, causing serious adverse health effects. Current clinical interventions for dysphagia are mainly empirical and often based on symptoms rather than etiology, of which a thorough understanding is still lacking. However, it is challenging to study the swallowing process that involves sequential structural motions and is inaccessible to standard visualization instruments. This study proposed an in vitro method to visualize swallowing hydrodynamics and identify the fundamental mechanisms underlying overflow aspirations. An anatomically accurate pharynx–epiglottis model was developed from patient-specific CT images of 623 µm isotropic resolution. A compliant half-pharynx cast was prepared to incorporate dynamic structures and visualize the flow dynamics in the mid-sagittal plane. Three locations of frequent overflow aspiration were identified: the epiglottis base, cuneiform tubular recesses, and the interarytenoid notch. Water had a consistently higher aspiration risk than a 1% w/v methylcellulose (MC) solution. The contracting–relaxing pharynx and flapping epiglottis spread the liquid film, causing a delayed esophageal entry and increased vallecular residual, which was more pronounced with the MC solution. Dispensing the liquid too slowly resulted in water aspiration, whereas this was not observed with the MC solution. An incomplete epiglottis inversion, such as horizontal or down-tilt 45°, aggravated the aspiration risks of water. This study suggests that it is practical to use anatomically accurate respiratory–digestive models to study the swallowing process by incorporating varying physiological details.

Drugs from nitroimidazole category are generally bitter in taste. Oral formulation with bitter taste is not palatable. Geriatrics and pediatrics patients usually suffer from swallowing difficulties. Many other patients in some disease conditions avoid swallowing tablets. Satranidazole is a new nitro-imidazole derivative with bitter taste and is available in market as film coated tablet. The purpose of this research was to mask the bitter taste of Satranidazole by coating complexation with low melting point wax and Eudragit EPO. Different types of wax (glyceryl monostearate, stearic acid and cetyl alcohol) were tried for taste masking. The drug to stearic acid ratio 1 : 2 was found to be optimum on the basis of taste evaluation and in vitro release. The formulated granules were found to possess good flow property. FTIR studies confirmed that there was no interaction between drug and excipients. Scanning Electron Microscopy of drug and the optimized batch of granules was performed. The in vitro release of drug from granules was compared with marketed tablet formulation. The taste masked granules of optimized batch showed 87.65% release of drug in 1 hr which is comparable to that of marketed tablet formulation.

Rekling, Jens C. and Jack L. Feldman. Calcium-dependent plateau potentials in rostral ambiguus neurons in the newborn mouse brain stem in vitro. J. Neurophysiol. 78: 2483–2492, 1997. The nucleus ambiguus contains vagal and glossopharyngeal motoneurons and preganglionic neurons involved in respiration, swallowing, vocalization, and control of heart beat. Here we show that the rostral compact formation's ambiguus neurons, which control the esophageal phase of swallowing, display calcium-dependent plateau potentials in response to tetanic orthodromic stimulation or current injection. Whole cell recordings were made from visualized neurons in the rostral nucleus ambiguus using a slice preparation from the newborn mouse. Biocytin-labeling revealed dendritic trees with pronounced rostrocaudal orientations confined to the nucleus ambiguus, a morphological profile matching that of vagal motoneurons projecting to the esophagus. Single-stimulus orthodromic activation, using an electrode placed in the dorsomedial slice near the nucleus tractus solitarius, evoked single excitatory postsynaptic potentials (EPSPs) or short trains of EPSPs (500 ms to 1 s). However, tetanic stimulation (5 pulses, 10 Hz) induced voltage-dependent afterdepolarizations or long-lasting plateau potentials (>1 min) with a constant firing pattern. Depolarizing or hyperpolarizing current pulses elicited voltage-dependent afterdepolarizations or plateau potentials lasting a few seconds to several minutes. Constant spike activity accompanied the long-lasting plateau potentials, which ended spontaneously or could be terminated by weak hyperpolarizing current pulses. Current-induced afterdepolarizations and plateau potentials were dependent on extracellularand intracellular Ca2+, as they were blocked completely by extracellular Co2+, Cd2+, or intracellular bis-( o-aminophenoxy)- N,N,N′,N′-tetraacetic acid (BAPTA). Orthodromically induced afterdepolarizations and plateau potentials were blocked by intracellular BAPTA. Afterdepolarizations and plateau potentials were completely blocked by substitution of extracellular Na+ with choline. Afterdepolarizations persisted in tetrodotoxin. We conclude that rostral ambiguus neurons have a Ca2+-activated inward current carried by Na+. Synaptic activation of this conductance may generate prolonged spike activity in these neurons during the esophageal phase of swallowing.

Les troubles de la déglutition sont l'une des principales causes de malnutrition et de déshydratation chez les personnes âgées. Cette étude présente une boîte à outils de méthodes précliniques pour évaluer les produits alimentaires destinés à pallier les symptômes des troubles de la salivation et de la déglutition. Une première illustration de cette approche concerne la conception de substituts salivaires naturels (SSN) et d'aliments semi-liquides à texture adaptée. Différents extraits naturels ont été produits et comparés à la salive humaine en termes de propriétés rhéologiques en cisaillement et en extension, ce qui a permis de sélectionner des formulations naturelles à base d'extraits de graines de lin au fort potentiel. La capacité de ces formulations à limiter les résidus oraux après déglutition a été confirmée à l'aide d'un simulateur de déglutition soft-robotique in vitro et par analyse sensorielle. L'impression 3D alimentaire a été aussi utilisée pour produire des aliments avec aux structures contrôlées afin d'adapter la texture d‘aliments solides. Une gamme intéressante de propriétés mécaniques a été obtenue. Les performances des NSS en matière d'hydratation et de lubrification de ces structures imprimées en 3D ont également été explorées in vitro.Cette étude démontre i) la pertinence de ces ou-tils précliniques, y compris les expériences in vitro simulant différents aspects de la transformation orale des aliments, pour faciliter le développement de produits alimentaires personnalisés et aliments destinés à des fins médicales spéciales ii) le fort potentiel des extraits de graines de lin comme SSN ou agent texturant, grâce à leurs propriétés rhéologiques et pouvoir lubrifiant et iii) l'intérêt de contrôler la structure des aliments par impression 3D, pour moduler leurs propriétés mécaniques et leur hydratation
Swallowing disorders, also known as dysphagia, are a leading cause of malnutrition and dehydration for older people. In this study, a toolbox of preclinical methods is developed to evaluate food products to manage swallowing disorders and xerostomia, the dry mouth sensation induced by the alteration of salivary flow rate.As a first illustration of the use of these preclinical tools, different natural extracts were produced and compared to human saliva, in terms of both shear and extensional rheological properties. The most promising formulations, obtained from flaxseed extracts, were used to formulate natural salivary substitutes (NSS) and texture adapted semi liquid foods, to promote lubrication and address the needs of people suffering from xerostomia. In addition, the ability of NSSs and modified semi liquid foods to limit post-swallowing oral residues was determined with an in vitro soft-robotic swallowing simulator and con-firmed by sensory analysis on healthy subjects.Three-dimensional printing was used to produce foods with controlled structures, resulting in different yielding behaviors, paving the way to texture adaptation to manage sarcopenia. NSS performance in terms of hydration and lubrication of these 3D-printed structures was also explored, in vitro.This study highlights i) the relevance of this pre-clinical toolbox, including the in vitro experiments simulating food oral processing, to support the development of personalized food products and food for special medical purposes ii) the peculiar rheological properties and lubricity of flaxseed ex-tracts and their strong potential as a NSS or texture modifier, and iii) the interest of controlling food structure via 3D printing to modulate food hydration and the mechanical and yielding behavior